This invention relates to video display apparatus and, in particular, to a method and apparatus for positioning and mounting of a degaussing coil on a cathode ray tube of a video display apparatus.
In order to remove residual magnetic fields resulting from the Earth""s magnetic field, and nearby electromagnetic fields, on the electron beam landing positions of a cathode ray tube in a video display apparatus, it is necessary to periodically demagnetize, or degauss, the metallic portions of the cathode ray tube. Degaussing is accomplished by passing a decaying alternating current through a wire coil that is distributed about the cathode ray tube. Typically, this occurs each time the video display apparatus, such as a television receiver, is energized or turned on.
It is important that the degaussing coil be positioned properly on the tube to insure complete degaussing. This is particularly important for cathode ray tubes having large deflection angles and/or tubes having small phosphor element spacing or pitch, which provide little tolerance for electron beam landing errors.
Many cathode ray tubes have mounting lugs attached thereto to facilitate mounting the cathode ray tube in a cabinet. The instant invention provides a retainer for a degaussing coil which can be easily attached to a mounting lug after the cathode ray tube has been mounted in its cabinet.
In accordance with an aspect of the present invention, an arrangement for a video display apparatus comprises a cathode ray tube having a neck and a faceplate coupled by a conical portion. The cathode ray tube has mounting lugs attached thereto for mounting said cathode ray tube in a cabinet. A degaussing coil is positioned against the conical portion of the cathode ray tube. A resilient clip having one end coupled to the degaussing coil and another end being snapped around one of the mounting lugs retains the degaussing coil in position against the conical portion of the cathode ray tube.
In accordance with another aspect of the invention, a method of securing a degaussing coil to a cathode ray tube, which is mounted in a cabinet by means of a lug, comprises the steps (not necessarily in order) of securing the degaussing coil to a resilient clip and snapping the clip around the lug.